Flying Boston’s Helicopter Routes for Six Months: Observations to Consider for Urban Air Mobility
The Bottom Line: I’ve been flying Boston’s helicopter routes for the last six months, and am happy to share with you some observations that have important implications for future commercial eVTOL operations. If we can continue this practice of incorporating the pilot’s experience flying existing routes and procedures in other cities around the world, we can be in a better position to validate (or invalidate) the assumptions we are making about how to best launch commercial eVTOL operations. There is only so much we can learn from what is published as opposed to actually going through the motions of these procedures, and the potential for variability that may be otherwise unforeseen. The introduction of such variability has important implications for how we plan to build a reliable commercial service, and what we can do now to prepare for a more favorable operating environment that can scale as demand grows.
As discussed in earlier articles, I view Urban Air Mobility (UAM) as the next chapter of an air taxi industry that traces its roots as far back as the 1940’s with the launch of Los Angeles Airways and New York Airways. To support this industry, regulators and communities have cooperated to create many of the procedures, routes, and infrastructure that we still use today. Now that batteries have reached a certain degree of maturity that can safely replace conventional engines, a much quieter aircraft with different capabilities, the electric vertical take-off and landing aircraft (eVTOL), will enter service.
With this in mind, industry has been hard at work planning the initial launch of this exciting service with a certain degree of comfort that many of the existing routes and procedures are applicable for eVTOL operations. Indeed, today’s current helicopter routes ought to support the initial volume of UAM flights with ease. However, as we look to the projected growth of UAM and the overall volume of eVTOL aircraft that are assumed to enter service, challenging operational questions for how these aircraft will fly, under what regulations, and with what, if any, support from air traffic control are being considered.
This following summary offers insight into my experience flying some of these routes in a Robinson 44 helicopter through Boston’s class “B” airspace, and the variation in procedures that can exist from controller to controller. This is not intended to be an exhaustive list, but rather the start of what I hope will be a growing catalogue of observations we can start collecting from flying our local helicopter routes and sharing similar observations with our regulators, working groups, and important industry stakeholders.
- Observation: Not all helicopter routes are eVTOL friendly. As you can see in the adjacent diagram, many of Boston’s helicopter routes are designed to fly over existing infrastructure like roads, railroad tracks, or bodies of water. They are designed with such visual aids to enable the pilot’s ability to maintain visual contact with the route which requires VFR conditions, and also so that the pilot will use these visual aids to maintain conformance to the published route. The design of these routes using roads or railroad tracks also has the additional benefit of minimizing impact to the underlying communities by asking pilots to fly where the ambient noise level is acceptable at higher levels.
Take-away: Because eVTOL aircraft will be electric, they will need to fly as direct as possible between their origin and destination so as to conserve energy. While some existing routes may allow for this, many others will not. It is also important to mention that flying on helicopter routes is not required. These routes exist to provide a structured way in, out, and around busy airspace for helicopters. However in many cases, there can be just as many “off-route” operations as “on-route”. If we wish to create procedures and routes for eVTOL aircraft that are community friendly, we will need to consider common eVTOL vehicle performance capabilities, the ability for eVTOL routes to absorb more volume as demand grows, and their impact on underlying communities.
2) Observation: Helicopter pilots operating on helicopter routes need to talk to Boston’s Logan tower. There are multiple helicopter routes in Boston that provide access to the city from all directions. As you continue to fly on a route “inbound”, it will eventually take you closer to Boston’s class “B” airspace which requires a specific clearance from ATC to enter. When flying on these routes, the procedure requires pilots to communicate with “Boston Skyways”, a dedicated helicopter frequency that is supported by Boston’s Logan (BOS) tower. When I depart from my home airport (OWD) heading to Boston, I call Skyways and let them know what route I want to take inbound and outbound (in and out of the city). If they can accommodate me, they will give me a 4-digit transponder code, grant me clearance into class “B” airspace, and provide the local altimeter setting. I will then maintain communication with them until I leave Boston’s class “B” airspace at which point they will cancel my transponder code or give me a new frequency to speak with another controller.
Take-away: This is a great service Boston tower provides, and it will certainly suffice for the initial volume of eVTOL flights should eVTOL service ever come to Boston. However, as the industry continues to scale, this paradigm of helicopter voice-based traffic management will become so overwhelming that it will no longer be offered, and an alternative will be needed. Furthermore, given that VFR traffic are never guaranteed clearance into class “B” airspace (priority is always given to IFR traffic first), a new type of infrastructure to facilitate access in and out of urban airspace is needed. Whether that may take the form of “exclusion zones”, VFR corridors or VFR transition routes, it behooves us to examine what the current paradigm is in each city and evaluate how much scalability that model has for eVTOL/UAM performance capabilities and limitations.
3) Observation: Helicopter pilots traditionally fly “on the right” in order to create some degree horizontal separation. In day operations, for example, this can be on a published route where pilots flying in opposite directions can fly on their own respective “right side”. For night operations, this can be done when using a highway to navigate. For emergency precautions, helicopter night operations suggest a route of flight close to well-lit areas, such as highways. In case the pilot needs to auto-rotate, it can be done in with a greater degree of visibility. With respect to observation #1, if a given city allows for UAM operations at night, this is another important aspect to consider for route design. To offer another example, flying on the right is also expected when navigating the VFR Hudson River corridor in New York City. As you can see in this image, southbound traffic fly on the west side of the river and northbound traffic fly on the east side.
Take-away: When flying VFR, which is expected for most helicopter routes, visual separation is critical for maintaining a safe environment. Agreed upon methods for horizontal separation, like flying on the right, is important, but it may not be enough when operations begin to scale. Furthermore, while pilots flying in the same direction have horizontal separation from opposing traffic, there doesn’t seem to be any procedures in place today for aircraft flying in the same direction, on the same route. When I speak with Boston’s “Skyways” frequency, they do share with me where other aircraft operating in my vicinity are, and to “maintain visual separation”. However, these services will not be available in the future if it is expected for eVTOL flights to operate outside controlled airspace and therefore will not be talking to air traffic control.
4) Observation: I am given low altitude restrictions when flying in Boston’s class “B” airspace. To remain clear of the arrivals and departures from Boston’s Logan airport, there are important altitude restrictions helicopter operations must obey. Sometimes I am told to stay below 1000 feet, but I am always expected to fly below 1500 ft MSL. Unless otherwise indicated, altitude assignments are given by the controller. As you can see in this picture, I flew the route between 800–900 ft MSL.
Take-away: There are three important implications for eVTOL flights that may fly on existing helicopter routes into controlled airspace with altitude restrictions to stay below 1000 ft. 1) To reiterate a previous point, clearance into Bravo airspace is never guaranteed for VFR aircraft, and in my experience, it is usually predicated upon controller workload.
With this in mind, it would be difficult to build a reliable UAM service around such variability. UAM route and operations planning will need to consider alternatives to the current procedure in Boston by establishing either VFR transition routes like what exists in Los Angeles today, or VFR corridors like what we have in the Hudson River in New York City, for example.
2) Altitude restrictions akin to what I experience in Boston may appear alarming to the underlying community, especially when more aircraft enter service. 3) It will be difficult to have vertical separation with these types of altitude restrictions which will become increasingly necessary as more aircraft enter service. There is a method for VFR aircraft flying in opposing directions, but current procedures allow for those rules to begin at altitudes exceeding 3000 feet. Since eVTOL aircraft will likely fly below this altitude, we will need to consider vertical separation requirements for UAM vehicles at UAM altitudes. Having flown the VFR Hudson River Corridor many times, I can share that it feels like flying in a “Bee’s nest”. Laguardia tower (Southbound) and Newark Tower (Northbound) certainly do their best to help each aircraft, but it can feel overwhelming to the most experienced pilot.
Finally, VFR aircraft in class “B” airspace needs to be clear of clouds with at least 3 statue miles of visibility. The ability to maintain clear of clouds in controlled airspace will be a further limiting factor to operations.
5) Observation: When I am cleared to enter Boston’s controlled airspace, Logan tower provides me with advisories regarding opposing traffic or other helicopters operating in my vicinity. This is a luxury for VFR flights in controlled airspace, and ATC can cancel their advisory service for VFR aircraft any time they want.
Take-away: Without advisories or radar separation services, the average cockpit is ill-equipped to meet the future needs of cooperative surveillance and deconfliction responsibilities. The need to see & avoid other aircraft is a responsibility that falls on the pilot during VFR operations, however today that is mostly done by looking outside and doing one’s best to stay clear of other aircraft. To help increase my ability to sense & avoid, I chose to invest in an ADS-B receiver which, when coupled with the appropriate app on my Ipad, allows me to see and avoid aircraft operating in my area. This capability dramatically helps my ability to stay clear of other aircraft, but it is still an uncommon cockpit accessory and is certainly not required equipment. At scale, the UAM industry will require such technology in the cockpit which is a far cry from what is mandated today. We must equip UAM pilots with all the cooperative surveillance information they can get, including similar information about UAS (drone) operations.
Conclusion
By actually flying the routes and procedures with the needs of the UAM industry in mind, we can start to “see around corners”, and anticipate what types of procedural and/or technological impediments can be expected so as to start developing more informed conclusions about our collective next steps. The routes and procedures we have today are a great start, and we are lucky to have them. Although my experience flying Boston’s helicopter routes are the source for these initial take-aways, it can certainly be argued that each city’s existing helicopter procedures will need to be reviewed by actually flying them in order to understand what similar, or different findings, can inform the launch of UAM in these respective environments. While the low altitude restrictions may be alarming for some, what concerns me most is the need for increased cooperative surveillance. While ADS-B “out” is mandated today for all aircraft, there no no such mandate for ADS-B “in”,which provides the type of visibility and awareness of a pilot’s surroundings that allows for “see and avoid” when we will not have the benefit of ATC services in the future. It is well documented that adding so many more aircraft to the 1090 frequency (used for ADS-B) will create congestion issues, which makes the case for new investment in cooperative surveillance technology even more critical for the safety case of UAM.
Since my team published our white paper, FlightPlan2030, we have been busy collaborating with air navigation service providers, regulators, airport authorities, peer organizations and communities. We are doing this to create a more favorable operating environment for the Urban Air Mobility ecosystem to grow naturally, without the type of procedural limitations we have reviewed in this article. We recently released a video which you can access here that summarizes our approach, and what you can expect for our next steps. Finally, our eVTOL proof of concept team is making great progress with our simulator which just released a video of their own here.
As always, if you have any questions or want to collaborate, please get in touch!
